1. Field of the Invention
This invention concerns a gas-lifting procedure, in general. More specifically, it deals with a procedure for gas-lifting products from a well that is used in an in situ heating procedure for producing petroleum products.
2. Description of the Prior Art
Gas-lift systems of different sorts have been used and known for many years in connection with producing liquids, particularly oil, from low pressure wells. For example, there is U.S. Pat. No. 3,054,358, to Merlyn et al, issued Sept. 18, 1962, which discloses a system that applies high pressure gas to the annulus of a well and has a pressure measuring element at the top of the well to measure the gas pressure therein. The system includes a gas-lift valve that is connected to a production tubing down in the hole. That valve will open when the level of fluid in the well reaches a particular height above it. The valve opening then permits high pressure gas (from the annulus) to force the fluid into the tubing and up the well. It does that until the gas pressure in the annulus has fallen to some particular low level. When that happens, a valve at the surface is opened to apply high pressure gas to the annulus once more, after sufficient time delay to allow the downhole gas-lift valve to close. Then, the increase of gas pressure in the annulus will act on the pressure measuring element at the top of the well so as to begin another cycle.
However, the system of that patent must employ a downhole gas-lift valve which is connected to the production tube. And, in addition, that patent system is not applicable to a method or system according to this invention because it introduces only high pressure gas to the well.